Eh. Lot of issues I see with this. Don't get me wrong, it's one of the better presented games in the Showcase right now, but when it comes to visuals I have a lot of criticism. Anyway, I'll start with the storyline. It seems fairly standard, though I think you need to give it a little more sensationalism. There's nothing enticing about it when I look at it currently, no actual talk of Pokemon, no real insight to the region and its history, I think you need to outline some sort of legend, surely you have some sort of legendary Pokemon. Try including it some how.

Going through your screens:

Spoiler:

I like the idea of swimming, though you have a clash of style in a couple places Those trees are really out of Pokemon style. I'll have some tiles o suit if you ever need them. They definitely need changing. The water seems pretty out of style, is it stock? It needs editing to meet the palettes better, or perhaps you need a more detailed one. The Slowpoke also needs a shadow.

You mapping needs a bit of work too. Here, here and here I can see tile errors in trees, namely missing edges, which are actually seen in most screenshots and not just those three. The grass tile you're using is pretty blotchy and not really detailed enough, I would recommend changing it as it's just too contrasted between the light green and the base green. The tree stumps you use, are also quite out of style, I'd have one or two I'd recommend you use instead. Your mountains need editing also, they're a completely different style to your ledges, and in fact they're meant for games with non-outlined tiles. Though your mapping does need work, as I say, the tall grass is quite iffy in a few places too. Your overworld could do with some work also. Your buildings need bigger doors too, they're FR/LG sized and you're using HGSS OW's.

However, in saying all this, I'm being quite negative I know, but there's so many positive points. The scripting looks pretty tight I have to say. The GUI's and such seem pretty cool, and overall style and quality of this is impressive. I'm jealous of that world map too! If you're in need of any assistance with the things I've mentioned, with graphics, mapping, anything (not to say you're not capable yourself), just let me know. Your game has a lot of potential and it's something I'd take pleasure in helping with if you needed me to.

At any rate, best of luck with this project, you seem quite knowledgeable so you should take this far.